Spark-plug



W. W. McELHATH, JR. SPARK PLUG. APPLICATION FILED Aue.25. 191s. RENEwEn-1uNE8, 1921.

Patented Aug. 2, 1921.

UNITED STATES PATENT oFFicE.

SPARK-PLUG,

Specification of Letters Patent.

Patented Aug. 2, 1921.

Application led August 25, 1919, Serial No. 319,547. Renewed June 8, 1921. Serial No. 476,109.

` To all whom t may concer/n Be it known that I, lWILLIAM W. Mo- ELRATH, Jr., a citizen of the United States, and a resident of East Radford, in the county of Montgomery and State of Virginia, have invented new 'and useful Improvements in Spark-Plugs, of which the following is a specilication.

This invention relates to spark plugs and has for its primary object the provision of a means whereby the carbon collecting upon the firing points or electrodes may be easily and quickly removed without necessarily removing the spark plug from the engine head.

A further object of the invention is'to provide in a spark plug a means whereby the gases under compression within the cylinder of an internal combustion engine may be prevented from escaping through the spark lug.

A further object of the invention is to provide in a spark plug of the above mentioned character a means whereby the sparking points or electrodes may be properly spaced one from the other without necessitating the removal of the spark plug from the engine head. i

Other objects and advantages of the invention will be apparent during the course of the following description taken in connection with the accompanying drawings.

In the drawings, forming a part of this specicationand wherein likenumerals are employed to designate like parts throughout the same,

Figure 1 is a central vertical sectional view through the spark plug embodying my invention, the various cooperation elements thereof being shown in their normal or functioning positions.

Fig. 2 is la similar view to that shown in Fig. 1, certain element-s thereof being shown in such positions as to enable the firing points or electrodes to be easily cleansed of carbon, and,

Fig. 3 is an end view of the spark plug embodying my invention.

In'the drawings, wherein for the purpose of illustration is shown a preferred form of my invention, the numeral 5 indicates a cy: l'indrical body provided at its lower end with screw-threads as shown, which screwthreads are adapted for engagement with the screw-threads of an internal combustion engine head, not shown. The cylindrical body 5 has an enlarged inner diameter at its upper end in order to provide a shoulder as shown at 6 and is provided with internal screw-threads as shown at 7, the internal screw-threads 7 being adapted for engagement with the'screw-threads of a gland nut 8. The gland nut 8 is 'provided at its lower end with a bevel as shown at 9 which is adapted to engage the bevel portion of preferably av porcelain insulating member 10. The gland nut 8 as is apparent serves as a means for retaining the porcelain insulating member 10 in position within the cylindrical body 5. As a means for preventing escapement of gas under pressure from within the cyllnder of the .engine there is provided a packing washer 11 which is disposed upon the shoulder 6 and adapted to receive thereupon the porcelain insulating member 10 as clearly shown. The porcelain insulating member 10 is at its lower end spaced from the inner wall of the cylinder member 5 and is provided .centrally with an enlarged opening 12 within which there is centrally disposed the lower end of an electrode or metallic conductor 13. The conductor 13 is provided with a shoulder as shown at 14, which shoulder is retained normally in engagement with a washer 15 arranged within the opening 12. The conductor or electrode 13 eX- tends centrally throughthe porcelain member 10 and is provided at its upper end with screw-threads as shown at 16, the screwthreaded end 16 being adapted for the reception of av nut 17 which serves as a means for retaining the electrode or conductor 13 in the position shown in Fig. 1. There is disposed also upon the screw-threaded end 16 of the conductora second nut 18 which is adapted to retain a suitable electric conductor in position upon the nut 17 and the elec- .trode 13. As a means for further preventing escapement of gas under pressure from the cylinder there is provided a packing 19 which is arranged within a counterbore 20 at the upper end of the porcelain member 10. Upon the packing 19 there is disposed a cylindrical member 21 which is normally retained firmly in contact with the packing 19 as shown in Fig. 1 by means of the nut 17. The lower end of the electrode 13 is provided with a stem 22 which terminates at its lower end in a head 23, which head is normally spaced a suitable distance Jfrom a conductor 24 suitably secured to the body of the cylindrical member 5.

In use, when it is desired to remove the carbon from the head 23 and the conductor 24, the nuts 17 and 18 are moved to approximately the position shown in F ig; 2 whereupon the electrode or conductor 13 is allowed to descend to the position shown in Fig. 2 thereby bringing the head 23 into contact with the conductor 24. By rotating the electrode or conductor 13 when in the ..compressed, thereby preventing the escapement of gas und-er compression from the cylinder through the opening provided for the reception of the elongated conductor 13. It is further apparent that by retaining the gland nut 8 firmly in contact with the beveled portion 9 ofthe porcelain 10 the gas under pressure is prevented from escaping from the cylinder around the porcelain insulating'm-ember 10.

' It is to be understood that the form of my invention herewith shown and described is to'be taken as a preferred example of the same, and that various changes-in the shape, size and arrangement of parts may be re- `sorted to without departing fromthe spirit of the invention or the scope of the subjoined claim.

Having thus described my invention, what I claim as new and desire to secure and protect by Letters Patent of the United States,

electrodes, an annular shoulder formed on the longitudinally movable electrodes and received in the lower end of the bore, a packing washer positioned on the longitudinally movable electrode and positioned on the upper face of the shoulder, a compressible packing element arranged in the upper end of the bore and positioned around the longitudinally movable electrode, a packing gland received upon the upper' end of the latter, and a jam nut threaded upon the upper end of said electrode to rotate thereon to engage the packingA gland to force the compressible element against said electrode and to move the same upwardly to Aspace the electrodes and to move the washer into engagement with the adjacent wall of the bore.

WILLIAM W. MCELRATH, JR. 

